Wire twisting pliers are used to twist safety wires that are typically used by aircraft mechanics to secure safety wire bolts from accidentally loosening from vibrations, such as those caused by aircraft engines. Safety wire nuts and bolts are used in a number of other applications as well, such as auto racing and industrial equipment. Wire twisting pliers typically include a conventional pair of pliers that is fitted with a locking mechanism and a rotating device. The locking mechanism locks the pliers on the wires that are to be twisted. The rotating device is manually operable to impart rotation of the pliers to thereby twist the wire. Such devices are disclosed in U.S. Pat. Nos. 4,842,025, 5,211,209, and 5,560,402
Wire twisting pliers twist a variety of wire sizes or gages depending on the job requirements. The most common sizes are 0.012″, 0.020″, 0.025″, 0.032″, 0.041″, and 0.051″. As the wire size increases, however, excessive jaw pressure is placed on the wire in order to lock the handles, making the handles difficult to lock and causing damage to the safety wire. This damage to the wire can cause premature failure of the safety wire in its application.
Additional problems can be encountered with the use of common wire twisting pliers. For example, wire twisting pliers are often used on wire bolts that are hard to reach, which causes the user to extend his or her hand/fingers/thumb beyond limitation in an effort to access portions of the tool. Also, during use, wire ends can be left spinning loose, which allows the wires to thrash around during twisting and potentially cause damage to the work piece or injuring the user. Additionally, standard teeth on plier jaws often distort and mar the wire, causing potential failure points in the wire strength. Moreover, safety wires are typically terminated by cutting the twisted wire, folding it over, and then crimping it in a tight loop known as a “pigtail.” Pigtails are difficult to accomplish with the bulky nose of existing wire twisters. Furthermore, when cutting the wire prior to twisting, care must be exercised so that the cut-off pieces do not fall into the surrounding machinery.